fiptool: Use getopt for the top level command parsing
fiptool: Use getopt for the top level command parsing

Change-Id: I18a4327e41fc090dcea9a647f7673182ca0ed1d9
Signed-off-by: dp-arm <5172875e934a989df22d22726b6d9d921b91fbdd@arm.com>

lsigithub/arm-trusted-firmware_public,sbranden/arm-trusted-firmware,achingupta/arm-trusted-firmware,lsigithub/arm-trusted-firmware_public,sbranden/arm-trusted-firmware,achingupta/arm-trusted-firmware